TWI418074B - An organic light-emitting device using a compound having a carrier transport property and a phosphorescent property - Google Patents

Abstract

Disclosed is an organic light-emitting device which contains one or more organic layers sandwiched between an anode and a cathode, wherein at least one of the organic layers is a light-emitting layer including a polymer compound (I), the polymer compound (I) containing structural units derived from a hole transport or electron transport and phosphorescent polymerizable compound (a1) and structural units derived from a polymerizable compound (b) capable of transporting an oppositely charged carrier, the polymerizable compound (a1) being selected from formulae (E1-1) to (E1-39) as defined herein.

Description

Use of an organic light-emitting element having a carrier transporting property and a phosphorescent compound

The present invention relates to an organic light-emitting element using a carrier-transporting and phosphorescent compound. More specifically, the present invention relates to an organic light-emitting device characterized in that a high luminous efficiency and durability can be obtained by using a compound having a carrier-transporting property and a phosphorescent property and containing a specific substituent.

The organic light-emitting element is known to be a multilayer structural element in which a light-emitting layer of a phosphorescent low molecular compound is provided between a hole transport layer and an electron transport layer.

On the other hand, in the industry, a phosphorescent polymer compound obtained by copolymerizing a phosphorescent polymerizable compound, a hole transporting polymerizable compound, and an electron transporting polymerizable compound has been developed. Since such a phosphorescent polymer compound has a function of phosphorescence, hole transport property, and electron transport property in one compound, it has a layer in which only one layer of the polymer compound is provided. The advantages of the organic light-emitting element can be obtained.

Conventionally, in order to synthesize the above-mentioned polymer compound, a polymerizable compound in which a polymerizable substituent is introduced on a conventionally known phosphorescent low molecular compound, a hole transporting low molecular compound, and an electron transporting low molecular compound ( Patent Documents 1 and 2 refer to).

However, when a phosphorescent low molecular compound suitable for a multilayer structure element is used and copolymerized with a hole transporting polymerizable compound and an electron transporting polymerizable compound, a large number of layers are formed. The case where the component is more susceptible to degradation.

Further, in the above polymer compound, it is difficult to efficiently generate an excited state in a structural unit of phosphorescence, and a high luminous efficiency is obtained. The polymer compound having all functions in a single layer is more in need of the energy level of each compound having phosphorescence, hole transportability, and electron transportability than the element for fabricating a multilayer structure. Combinations result in extreme difficulty in the choice of each compound.

Further, in order to improve the light-emitting efficiency, when a polymer compound having a structural unit containing phosphorescence at a high concentration is used, it is known that concentration extinction is generated instead, and as a result, high luminous efficiency cannot be obtained.

Patent Document 1: JP-A-2002-293830, Patent Document 2: JP-A-2003-73479

Invention disclosure

An object of the present invention is to provide an organic light-emitting element having high luminous efficiency and excellent durability.

As a result of intensive studies, the present inventors have found that an organic light-emitting element having high luminous efficiency and excellent durability can be obtained by using a compound having carrier transportability and phosphorescence property and containing a specific substituent. Thus, the present invention has been completed.

That is, the present invention is as follows.

[1] An organic light-emitting device characterized by being contained in an organic light-emitting device comprising at least one organic layer sandwiched between an anode and a cathode, wherein at least one layer of the organic layer contains a polymer compound (I) a light-emitting layer, and the polymer compound (I) has a structural unit derived from a carrier-transporting property and a phosphorescent property of the polymerizable compound (a1) having either a hole transporting property and an electron transporting property, and The structural unit derived from the carrier-transporting polymerizable compound (b) of the other, and the polymerizable compound (a1), which is selected from the group consisting of the following formulae (E1-1) to (E1-39) , (In the formula (E1-1), at least one of the hydrogen atoms is selected from a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and a carbon number of 1 to 10 Substituting a group of an alkyl group-substituted amine group, a carbon number of 1 to 10 alkoxy group, and a germyl group, and at least one of the hydrogen atoms is the following general formula (H1) a polymerizable substituent; wherein R ²⁵ is a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms; a hydrogen atom in the formula (E1-2) to formula (E1-39) is also a formula (E1) -1) The hydrogen atoms in the same are the same).

[2] The organic light-emitting device according to the above [1], wherein the polymerizable compound (a1) has carrier transportability and phosphorescence property of hole transportability, and the polymerizable compound (b) has electron transport property. Carrier transporter.

[3] The organic light-emitting device according to the above [1], wherein the polymerizable compound (a1) has electron transport property carrier transport property and phosphorescence property, and the polymerizable compound (b) has hole transport property. Carrier transporter.

[4] The organic light-emitting device according to the above [2], wherein the polymerizable compound (a1) is represented by the above formula (E1-1).

[5] An organic light-emitting device characterized by being contained in an organic light-emitting device comprising at least one organic layer sandwiched between an anode and a cathode, wherein at least one layer of the organic layer contains a polymer compound (II) In the light-emitting layer, the polymer compound (II) has a carrier-transporting property and a phosphorescent property (a2) having either carrier transportability and electron transport property, and a carrier having the other carrier The structural unit derived from the transportable polymerizable compound (b), and the compound (a2) is selected from the group consisting of the following formulae (E2-1) to (E2-39). (In the formula (E2-1), at least one of the hydrogen atoms is selected from a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and a carbon number of 1 to 10 a substituent substituted by an alkyl group-substituted amine group, a carbon number of 1 to 10 alkoxy group, and a germyl group; a hydrogen atom in the formula (E2-2) to (E2-39), It is also the same as the hydrogen atom in the formula (E2-1).

[6] The organic light-emitting device according to the above [5], wherein the compound (a2) has carrier transportability and phosphorescence property of hole transportability, and the polymerizable compound (b) is transportable by electron transport. Sex.

[7] The organic light-emitting device according to the above [5], wherein the compound (a2) has carrier transportability and phosphorescence property of electron transport property, and the polymerizable compound (b) has carrier transport property of hole transportability Sex.

[8] The organic light-emitting device according to the above [6], wherein the compound (a2) is represented by the above formula (E2-1).

[9] The organic light-emitting device according to any one of the above [1], wherein the polymer compound (I) contains a structure derived from the polymerizable compound (a1) in a total structural unit. The unit is 3 to 60% by weight.

[10] The organic light-emitting device according to any one of the above [5], wherein the light-emitting layer contains the compound (a2) with respect to the total amount of the compound (a2) and the polymer compound (II). ) is 3 to 60% by weight.

[11] The organic light-emitting device according to any one of the above [1], wherein the light-emitting layer contains the compound (d), and the compound (d) has a lower affinity than the polymerizable compound (a1). The phosphorescence of the energy luminescence.

[12] The organic light-emitting device according to any one of [5] to [8] wherein the light-emitting layer contains the compound (d) having a lower energy than the compound (a2) Phosphorescence of luminescence.

[13] A display device characterized by using the organic light-emitting device of the above [1] or [5].

[14] A surface light-emitting source characterized by using the organic light-emitting device of the above [1] or [5].

[15] A backlight for a display device, characterized in that the organic light-emitting device of the above [1] or [5] is used.

[16] An illuminating device characterized by using the organic light-emitting device of the above [1] or [5].

[17] An interior decoration characterized by using the organic light-emitting device of the above [1] or [5].

[18] An outdoor decoration characterized by using the organic light-emitting element according to the above [1] or [5].

According to the present invention, since a compound having a carrier transporting property and a phosphorescent property and containing a specific substituent is used, an organic light-emitting device having high luminous efficiency and excellent durability can be obtained.

Best form for implementing the invention

Hereinafter, the present invention will be specifically described.

1. Composition of organic light-emitting elements

The organic light-emitting device of the present invention contains at least one organic layer sandwiched between the anode and the cathode, and at least one of the organic layers contains a light-emitting layer.

An example of the configuration of the above organic light-emitting element is shown in Fig. 1, but the configuration of the element is not limited to this range. In Fig. 1, between the anode (2) and the cathode (6) provided on the transparent substrate (1), a hole transport layer (3), a light-emitting layer (4), and an electron transport layer are successively provided ( 5).

In the above organic light-emitting device, for example, either one of the hole transport layer/light-emitting layer and 2) the light-emitting layer/electron transport layer may be disposed between the anode (2) and the cathode (6), or It is possible to set only 3) a separate layer of the luminescent layer. Furthermore, it is also possible to laminate two or more light-emitting layers; an anode buffer layer may be disposed between the anode (2) and the hole transport layer (3); or in the light-emitting layer (4) and the electron transport layer (5) A hole blocking layer can also be provided between. Further, 4) a layer containing a hole transporting compound, a light-emitting compound, or an electron transporting compound; 5) a layer containing a hole transporting compound or a light-emitting compound; and 6) a light-emitting compound; The layer of the electron transporting compound; 7) contains a compound having a hole transporting property and an electron transporting property, and a layer of a light-emitting compound.

Each of the above layers may be formed by mixing a polymer material as a binder. Examples of the polymer material include polymethyl methacrylate, polycarbonate, polyester, polyfluorene, and polyphenylene ether.

Further, in the present specification, at least one compound selected from the group consisting of an electron transporting compound, a hole transporting compound, and a light-emitting compound is also referred to as an organic electroluminescent light (also referred to as an organic EL in the present specification). . The layer formed from this compound is also referred to as an organic EL compound. Further, a hole transporting compound, an electron transporting compound, and a compound having a hole transporting property and an electron transporting property are also referred to as a carrier transporting compound.

2. Light-emitting layer

The light-emitting layer used in the present invention may be: [A] a light-emitting layer containing the polymer compound (I); or [B] a light-emitting layer containing the compound (a2) and the polymer compound (II); The light-emitting layer of the polymer compound (I) and the compound (d); or [D] the light-emitting layer containing the compound (a2), the polymer compound (II) and the compound (d).

<Light Emitting Layer [A]>

The light-emitting layer [A] contains a polymer compound (I) having a structural unit derived from the polymerizable compound (a1) and a structural unit derived from the polymerizable compound (b). The polymer compound (I) is obtained by copolymerization of a polymerizable compound (a1) and a polymerizable compound (b).

The polymerizable compound (a1) has either carrier transportability and electron transport property, and has carrier transportability and phosphorescence, and is selected from the above formulae (E1-1) to (E1-39). Group of people. The polymerizable compound (a1) may be used alone or in combination of two or more kinds as long as it has the same carrier transport property.

In the formula (E1-1), at least one of the hydrogen atoms is selected from a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and a carbon number of 1 to 10. A substituent substituted by an alkyl group-substituted amine group, a carbon number of 1 to 10 alkoxy group, and a germyl group.

The above halogen atom may, for example, be a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

The alkyl group having 1 to 10 carbon atoms may, for example, be a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, an octyl group or a decyl group.

The above aryl group having 6 to 10 carbon atoms, for example, a phenyl group, a tolyl group, a xylyl group, Base, naphthyl and the like.

The above-mentioned amine group which may be substituted with an alkyl group having 1 to 10 carbon atoms may, for example, be an amine group, a dimethylamino group, a diethylamino group or a dibutylamino group.

The above alkoxy group having 1 to 10 carbon atoms, for example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a t-butoxy group, a hexyloxy group, and 2 - Ethylhexyloxy, decyloxy and the like.

The above-mentioned germyl group may, for example, be trimethylmethanealkyl, triethylcarbenyl, t-butyldimethylformamidin or the like.

Among them, a fluorine atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, a tolyl group, a dimethylamino group, and an alkoxy group having 1 to 4 carbon atoms are preferred, and a fluorine atom, t- Butyl, dimethylamino and methoxy are preferred.

In the formula (E1-1), one of the hydrogen atoms represents a polymerizable substituent represented by the above formula (H1). Wherein R ²⁵ represents a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms. Among them, a methyl group, an ethyl group and a propyl group are preferred.

The polymerizable substituent may be a substituent bonded to the ruthenium complex by interposing an organic group having 1 to 20 carbon atoms composed only of a hydrocarbon containing no hetero atom.

Specifically, the polymerizable substituent is preferably a substituent represented by the following general formulas (A1) to (A11).

Even the hydrogen atom in the formula (E1-1) to (E1-39) is the same as the hydrogen atom in the formula (E1-1).

The polymerizable compound (b) is a carrier transporting property having a hole transporting property or an electron transporting property. The polymerizable compound (b) is not particularly limited as long as it contains a polymerizable substituent, and a conventional carrier-transporting compound can be used. The polymerizable compound (b) may be used alone or in combination of two or more kinds as long as it has the same carrier transport property.

The polymerizable substituent is a synonymous with a polymerizable substituent in the polymerizable compound represented by the above formula (E1-1), and the preferred range thereof is also the same.

The carrier transportability (b) having a hole transporting property is preferably a compound represented by the following formulas (F1) to (F9).

The carrier transportability (b) having electron transport property is preferably a compound represented by the following formulas (G1) to (G9).

Further, in the above (F1) to (F9) and (G1) to (G9), the polymerizable substituent may be represented by the above formula (A1), but it is only a polymerizable substituent represented by the above formula (H1). Just fine.

(1) When the polymerizable compound (a1) has a carrier property of phosphorescence and hole transportability, the polymerizable compound (b) has electron transport property carrier transportability; and (2) a polymerizable compound (a1) When the carrier transport property of the phosphorescent property and the electron transport property is simultaneously provided, the polymerizable compound (b) is a carrier transporting property having a hole transporting property. In the case of either (1) or (2), only two kinds of compounds are copolymerized to obtain a polymer compound having all functions of phosphorescence, hole transportability, and electron transport property. . In comparison with a polymer compound which conventionally uses three kinds of compounds having respective functions, a compound which is used as a monomer has a small amount of a compound, and a polymer compound excellent in durability can be obtained. In addition, since only two kinds of compounds are selected, the adjustment of the energy level is easier than the conventional one. Further, since the polymerizable compound (a1) has both carrier transportability and phosphorescence, it can generate an exciton at a higher accuracy in the structural unit derived from the polymerizable compound (a1). Achieve a high degree of luminous efficiency.

In the light-emitting layer [A], the above formula (E1-1) having a hole transporting property and a phosphorescent property as the polymerizable compound (a1) is particularly a polymerization represented by the following formula (E1-1-1). The combination of the compound and the polymerizable compound (b) having electron transport property is preferable because it can produce an element which is more excellent in luminous efficiency and durability.

In the formula (E1-1-1), at least one of R ₁ ¹ to R ₁ ²⁴ represents an aryl group selected from a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, and a carbon number of 6 to 10. The substituent may be a group of an amine group substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a methyl group. One of R ₁ ¹ to R ₁ ²⁴ represents a polymerizable substituent. The above polymerizable substituent is synonymous with the above substituent, and the preferred range thereof is also the same.

Further, in the light-emitting layer [A], a polymerizable compound having a carrier transport property and a transport property of electron transportability as a polymerizable compound (b), that is, generally referred to as "bipolar", may be used. A polymeric compound of a nature. The above-mentioned bipolar polymerizable compound is generally superior in any of the hole transporting property and the electron transporting property, and when the compound is used, the carrier can be obtained by the carrier transportability of the polymerizable compound (a1).

The above bipolar polymerizable compound is specifically, for example, 4,4'-n,n'-dicarbazolebiphenyl (CBP).

The polymer compound (I) preferably contains 3 to 60% by weight of the structural unit derived from the polymerizable compound (a1), and preferably 15 to 30% by weight in the total structural unit. The amount of the structural unit is determined by ICP elemental analysis and ¹³ C-NMR measurement. In the polymer compound (I) used in the present invention, the polymerizable compound (a1) has a specific substituent as described above, and even if it contains a plurality of structural units derived from the polymerizable compound (a1), it can be obtained. A light-emitting layer which is excellent in film formability and high in durability. Further, it is possible to obtain a person who does not easily generate concentration extinction and has high luminous efficiency.

Further, the molecular weight of the polymer compound (I) preferably has a weight average molecular weight of 1,000 to 2,000,000, and most preferably 20,000 to 100,000. Here, the weight average molecular weight is a value measured by a gel permeation chromatography (GPC) method and using tetrahydrofuran as a solvent at 40 °C.

The polymer compound (I) may be any of a random copolymer, a block copolymer, and an interactive copolymer.

The polymerization method of the polymer compound (I) may be any of radical polymerization, cationic polymerization, anionic polymerization, and addition polymerization, but radical polymerization is preferred. For the polymerization method of the above-mentioned polymer compound, more specifically, for example, JP-A-2003-342325, JP-A-2003-119179, JP-A-2003-113246, JP-A-2003-206320 Japanese Laid-Open Patent Publication No. 2003-147021, JP-A-2003-171391, JP-A-2004-346312, and JP-A-2005-97589.

The method for producing the light-emitting layer [A] is not particularly limited, and can be produced, for example, as follows. First, a solution in which the polymer compound (I) is dissolved is prepared. The solvent to be used in the preparation of the above solution is not particularly limited. For example, a chlorine solvent such as chloroform, dichloromethane or dichloroethane, an ether solvent such as tetrahydrofuran or anisole, or toluene or xylene can be used. An aromatic hydrocarbon solvent, a ketone solvent such as acetone or methyl ethyl ketone, or an ester solvent such as ethyl acetate, butyl acetate or ethyl cellosolve acetate. Next, the solution thus prepared is subjected to spin coating, casting, microgravure coating, gravure coating, rod coating, roll coating, copper bar coating, and deep coating. A wet film formation method such as a method, a spray coating method, a screen printing method, a flexographic printing method, an offset printing method, or an inkjet printing method is used to form a film on a substrate. In the spin coating method or the deep layer method, for example, the solution containing the polymer compound (I) in an amount of 0.5 to 5% by weight is preferred, for example, in the spin coating method or the deep layer method.

<Light Emitting Layer [B]>

The light-emitting layer [B] contains a polymer compound (II) having a structural unit derived from the compound (a2) and the polymerizable compound (b). The polymer compound (II) is obtained by polymerizing the polymerizable compound (b).

The polymerizable compound (a2) has either carrier transportability and electron transport property, and has carrier transportability and phosphorescence, and is selected from the above formulae (E2-1) to (E2-39). Group of people. The compound (a2) may be used alone or in combination of two or more kinds as long as it has the same carrier transport property.

In the formula (E2-1), at least one of the hydrogen atoms is selected from a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, and a carbon number of 1 to 10. A substituent substituted by an alkyl group-substituted amine group, a carbon number of 1 to 10 alkoxy group, and a germyl group. Preferred substituents are the same as those of the formula (E1-1).

The hydrogen atom in the formula (E2-2) to (E2-39) is also the same as the hydrogen atom in the formula (E2-1).

The polymerizable compound (b) is a carrier transporting property having a hole transporting property or an electron transporting property. The polymerizable compound (b) is not particularly limited as long as it contains a polymerizable substituent, and a conventional carrier-transporting compound can be used. The polymerizable compound (b) may be used alone or in combination of two or more kinds as long as it has the same carrier transport property.

The polymerizable substituent is a synonymous with a polymerizable substituent in the polymerizable compound represented by the above formula (E1-1), and the preferred range thereof is also the same.

The carrier transportability (b) having a hole transport property is preferably a compound represented by the above formulas (F1) to (F9); a carrier transportability (b) having electron transport property, preferably using the above formula ( Compound represented by G1)~(G9). Further, in the above formulae (F1) to (F9) and (G1) to (G9), the polymerizable substituent may be represented by the above formula (A1), but it is only a polymerizable substitution represented by the above formula (H1). The base can be.

Further, the molecular weight of the polymer compound (II) preferably has a weight average molecular weight of 1,000 to 2,000,000, and most preferably 20,000 to 100,000. Here, the weight average molecular weight is a value measured by a gel permeation chromatography (GPC) method and using tetrahydrofuran as a solvent at 40 °C.

The polymerization method of the polymer compound (II) may be any of radical polymerization, cationic polymerization, anionic polymerization, and addition polymerization, but radical polymerization is preferred. These polymer compounds can be obtained by a conventional method.

(1) When the compound (a2) has a carrier property of phosphorescence and hole transportability, the polymerizable compound (b) has electron transport property carrier transportability; and (2) a polymerizable compound (a2) When the carrier transport property of phosphorescence and electron transport property is simultaneously provided, the polymerizable compound (b) has a carrier transport property of hole transportability. In the case of either (1) or (2), only two kinds of compounds are copolymerized to obtain a polymer compound having all functions of phosphorescence, hole transportability, and electron transport property. . Therefore, the durability is also excellent. In addition, since only two kinds of compounds are selected, the adjustment of the energy level is easier than the conventional one. Further, since the compound (a2) has both carrier transportability and phosphorescence, it can produce an excited state with higher accuracy on the compound (a2), and a high luminous efficiency can be obtained.

In the light-emitting layer [B], the above formula (E2-1) having a hole transporting property and a phosphorescent property as the compound (a2) is particularly a polymerizable compound represented by the following formula (E2-1-1). The polymer compound (II) having a structural unit derived from the electron transporting polymerizable compound (b) is preferably a combination of elements which are more excellent in luminous efficiency and durability.

In the formula (E2-1-1), at least one of R ₂ ¹ to R ₂ ²⁴ represents an aryl group selected from a halogen atom, a cyano group, an alkyl group having 1 to 10 carbon atoms, and a carbon number of 6 to 10. The substituent may be a group of an amine group substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and a methyl group.

Further, in the light-emitting layer [B], a polymerizable compound having a carrier transport property and a transport property of electron transportability as a polymerizable compound (b), that is, generally referred to as "bipolar", may be used. A polymeric compound of a nature. The above-mentioned bipolar polymerizable compound is generally superior in any of the hole transporting property and the electron transporting property, and when the compound is used, the carrier can be obtained by the carrier transportability of the compound (a2).

The above bipolar polymerizable compound is specifically, for example, 4,4'-n,n'-dicarbazolebiphenyl (CBP).

The light-emitting layer [B] preferably contains the compound (a2) in an amount of from 3 to 60% by weight, preferably from 15 to 30% by weight, based on the total amount of the compound (a2) and the polymer compound (II). Since the compound (a2) used in the present invention has a specific substituent as described above, it is excellent in film formability, particularly dispersibility, and can be used in a high concentration. Further, since the dispersibility is excellent, a highly durable light-emitting layer can be obtained. Further, it is possible to obtain a person who does not easily generate concentration extinction and has high luminous efficiency.

The method for producing the light-emitting layer [B] is not particularly limited, and can be produced, for example, as follows. First, a solution in which the compound (a2) and the polymer compound (II) are dissolved is prepared. The solvent to be used in the production of the above solution is not particularly limited, and a solvent similar to the case of the light-emitting layer [A] can be used. Next, the solution thus prepared was formed on the substrate in the same manner as in the case of the light-emitting layer [A]. Although depending on the compound, the film formation conditions, and the like, for example, in the spin coating method or the deep layer method, the solution has a solid concentration of 0.5 to 5% by weight, and contains a compound (a2) in relation to the solid content. The amount of the polymer compound (II) is preferably from 85 to 70% by weight, and is preferably from 85 to 70% by weight.

<Light Emitting Layer [C]>

The light-emitting layer [C] is preferably a compound (d) containing a phosphorescent property which emits light at a lower energy than the polymerizable compound (a1).

In this case, the polymer compound (I) is used as a main component. Since the polymer compound (I) is excellent in both durability and carrier transportability, energy transfer can be efficiently performed on the compound (d), and the compound (d) can emit light with high efficiency.

The compound (d) is not particularly limited as long as it can emit light at a lower energy than the polymerizable compound (a1). The compound (d) may be used singly or in combination of two or more kinds. For example, when a compound of cyan light is used as the polymerizable compound (a1), a compound (d) which emits green, yellow or red light can be used; for example, a compound which emits green light is used as the polymerizable compound (a1). When used, a compound (d) which emits yellow or red light can be used; and when a compound which emits yellow light is used as the polymerizable compound (a1), a compound (d) which emits red light can be used. Here, the energy of the luminescence of the compound means the value of the excitatory energy obtained by the absorption wavelength or the luminescence wavelength measured by the spectrophotometer.

The light-emitting layer [C] preferably contains the polymer compound (I) in an amount of from 99.5 to 80% by weight, and the compound (d) is 0.5%, based on the total amount of the polymer compound (I) and the compound (d). An amount of 20% by weight is desirable.

The method for producing the light-emitting layer [C] is not particularly limited, and can be produced, for example, as follows. First, a solution in which the polymer compound (I) and the compound (d) are dissolved is prepared. The solvent to be used in the production of the above solution is not particularly limited, and a solvent similar to the case of the light-emitting layer [A] can be used. Next, the solution thus prepared was formed on the substrate in the same manner as in the case of the light-emitting layer [A]. Depending on the compound to be used, the film formation conditions, and the like, for example, in the spin coating method or the deep layer method, the solid solution concentration of the above solution is 0.5 to 5% by weight, and is high relative to the total amount of the solid component. The molecular compound (I) is preferably from 99.5 to 80% by weight, and the compound (d) is preferably from 0.5 to 20% by weight.

<Light Emitting Layer [D]>

The light-emitting layer [D] is preferably a compound (d) containing a phosphorescent property which emits light at a lower energy than the compound (a2).

In this case, the compound (a2) and the polymer compound (II) are used as a main component. The light-emitting layer formed of the compound (a2) and the polymer compound (II) is excellent in durability and carrier transportability, and the compound (d) can efficiently generate energy transfer, and the compound (d) can Lights up with high efficiency.

The compound (d) is not particularly limited as long as it can emit light at a lower energy than the compound (a2), similarly to the light-emitting layer [C]. The compound (d) may be used singly or in combination of two or more kinds.

The light-emitting layer [D] preferably contains the compound (a2) in an amount of 15 to 30% by weight based on the total amount of the compound (a2), the polymer compound (II), and the compound (d), and contains a polymer compound ( I) is preferably from 70 to 85% by weight, and the compound (d) is preferably from 0.5 to 20% by weight.

The method for producing the light-emitting layer [D] is not particularly limited, and can be produced, for example, as follows. First, a solution in which the compound (a2), the polymer compound (II), and the compound (d) are dissolved is prepared. The solvent to be used in the production of the above solution is not particularly limited, and a solvent similar to the case of the light-emitting layer [A] can be used. Next, the solution thus prepared was formed on the substrate in the same manner as in the case of the light-emitting layer [A]. Depending on the compound to be used, the film formation conditions, and the like, for example, in the spin coating method or the deep layer method, the solution has a solid concentration of 0.5 to 5% by weight, and contains a compound in an amount relative to the solid content. The amount of (a2) is 15 to 30% by weight, and the amount of the polymer compound (I) is 70 to 85% by weight, and the compound (d) is preferably 0.5 to 20% by weight.

3. Other layers

Hereinafter, the layer used in the organic light-emitting device of the present invention will be described.

<Anode buffer layer: When using a conductive film, etc.>

The compound to be used in the above anode buffer layer is not particularly limited as long as it has a good adhesion to the surface of the anode and the upper layer thereof, and is, for example, polyethylidene dihydroxythiophene (PEDOT) and polystyrene. A conventional conductive polymer such as a mixture of sulfonic acid (PSS), a mixture of polyaniline and polystyrene sulfonate (PANI), or the like. An organic solvent such as toluene or isopropyl alcohol may be added to the conductive polymer. Further, it may be a conductive polymer containing a third component such as a surfactant. The above surfactant may, for example, contain an alkyl group, an alkylaryl group, a fluoroalkyl group, an alkyl alkane, a sulfate, a sulfonate, a carboxylate, a guanamine, a betaine structure, a fourth-order ammonium group. Surfactants, etc., but a nonionic surfactant of a fluoride matrix can also be used.

<hole blocking layer>

Further, the hole block layer may be provided adjacent to the cathode side of the light-emitting layer for the purpose of suppressing the passage of the hole through the light-emitting layer and efficiently recombining the hole and the electron in the light-emitting layer. In the hole block layer, a compound having a higher occluded Molecular Orbital (HOMO) level, which is, for example, a triazole derivative or a dioxin, may be used. An azole derivative, a phenanthroline derivative, an aluminum complex, and the like.

Further, for the purpose of preventing the exciter from being deactivated by the cathode metal, an excitatory sub-barrier layer may be provided adjacent to the cathode side of the light-emitting layer. In the exciton sub-blocking layer, a compound having a higher triplet energy of a light-emitting compound is used, and the compound specifically includes, for example, a triazole derivative, a phenanthroline derivative, an aluminum complex, or the like. .

<Formation of each layer>

Each of the above layers may be a dry film forming method such as a resistance heating vapor deposition method, an electron beam evaporation method, or a sputtering method, and may be subjected to a spin coating method, a casting method, a micro gravure coating method, or a gravure coating method. , rod coating method, roll coating method, copper bar coating method, deep coating method, spray coating method, screen printing coating method, flexographic printing coating method, offset printing coating method, spraying It is formed by a wet film formation method such as an ink printing method. In the case of a low molecular compound, a dry film formation method is preferably used; and in the case of a polymer compound, a wet film formation method is preferably used.

<anode>

When the anode material used in the organic light-emitting device of the present invention is observed by light-emitting through the substrate, it is preferable to use, for example, ITO (indium tin oxide), tin oxide, zinc oxide, polythiophene, polypyrrole, polyaniline or the like. A known transparent conductive material such as a polymer. In addition, on the ITO surface, a metal film of 1 to 3 nm can be provided without damaging the light transmittance. Examples of the metal include gold, nickel, manganese, ruthenium, molybdenum, palladium, platinum, and the like.

Furthermore, if the light is transmitted through the upper electrode (Top Emission), the anode does not need to be penetrating. Therefore, as such an anode material, for example, a metal or a metal compound having a work function higher than 4.1 eV can be preferably used. Specifically, for example, it is the same as the above metal. These metals may be used singly or in combination of two or more.

The surface resistance of the anode is preferably 1 to 50 Ω/□ (ohm/square), and the thickness of the anode is preferably 2 to 300 nm.

For the film formation method of the anode, for example, a vacuum deposition method, an electron beam deposition method, a sputtering method, a chemical reaction method, a coating method, or the like can be used.

<Anode surface treatment>

Further, in the case of forming an anode buffer layer or the like, the function of the anode buffer layer or the like (adhesion to the anode substrate, surface smoothness, reduction of hole injection barrier, etc.) can be performed by the surface treatment of the anode surface. improve. The above pretreatment method starts with high-frequency plasma treatment, and is, for example, a sputtering treatment, a corona treatment, a UV ozone irradiation treatment, an oxygen plasma treatment, or the like.

<cathode>

The cathode material of the organic light-emitting device of the present invention is not particularly limited as long as it has a low work function and is chemically stable, and preferably, for example, an alkali metal such as Li, Na, K, or Cs can be used; Alkaline earth metals such as Ca and Ba; Al; MgAg alloy; Al and alkali metal alloys such as AlLi and AlCa. If the chemical stability is considered, it is preferable to use a work function of 2.9 eV or less. The thickness of the cathode is preferably 10 nm to 1 μm, and is preferably 50 to 500 nm.

As the film forming method of the cathode, for example, a resistance heating vapor deposition method, an electron beam evaporation method, a sputtering method, an ion coating method, or the like can be used.

Further, a cathode buffer layer may be provided for the purpose of reducing the electron injection barrier from the cathode to the organic layer and increasing the electron injection efficiency. The cathode buffer layer may be a metal layer having a lower work function than the cathode and interposed between the cathode and the organic layer adjacent to the cathode. Examples of the metal used in the cathode buffer layer include alkali metals (Na, K, Rb, and Cs), alkaline earth metals (Sr, Ba, Ca, and Mg), and rare earth metals (Pr, Sm, Eu, and Yb). Wait. Further, as long as the work function is lower than that of the cathode, an alloy, a metal compound or the like can be used. The thickness of the buffer layer is preferably 0.05 to 50 nm, more preferably 0.1 to 20 nm, and most preferably 0.5 to 10 nm.

Further, the cathode buffer layer may be formed into a mixture with the above-described low work function metal or the like and an electron transporting compound. As the electron transporting compound, the above-exemplified compounds can be used. The thickness of the cathode buffer layer is preferably 0.1 to 100 nm, more preferably 0.5 to 50 nm, and most preferably 1 to 20 nm.

Further, a layer made of a conductive polymer, a metal oxide, a metal fluoride, or a layer made of an organic insulating material (a layer having an average film thickness of 2 nm or less) may be provided between the cathode and the organic layer. )Wait.

As the film formation method of the cathode buffer layer, a vapor deposition method, a co-evaporation method, a sputtering method, or the like can be used. Further, depending on the material to be used, a film forming method such as a spin coating method, a deep coating method, an inkjet method, a printing method, a spray method, or a quantitative dosing method may be used.

<Substrate>

In the substrate of the organic light-emitting device of the present invention, an insulating substrate transparent to the light-emitting wavelength of the above-mentioned light-emitting material can be preferably used. Specifically, in addition to glass, PET (polyethylene terephthalate) can be used. , transparent plastics such as polycarbonate.

<closed>

After the cathode is fabricated, a protective layer and/or a protective cover may be provided to protect the organic light-emitting element. Thereby, the durability of the above organic light-emitting element can be improved. As the protective layer, a layer formed of a polymer compound, a metal oxide, a metal fluoride, a metal boride or the like can be used. The protective cover may be a glass plate, a plastic plate having a low water permeability treatment applied to the surface, a metal, or the like, and the protective cover is preferably a sealing method in which a heat-resistant resin, a photo-curable resin, or the like is attached to the element substrate.

Furthermore, if a space is used to maintain the space, the component is less likely to be damaged. When an inert gas such as nitrogen or argon is blocked in the space, oxidation of the cathode can be prevented. Further, by providing a desiccant such as ruthenium oxide in the space, it is possible to suppress damage of the element due to moisture adsorption in the production step. Among them, a strategy of adopting either or more is preferred.

4. Use

In order to obtain the pattern-like illuminating light using the organic light-emitting device of the present invention, for example, a method of providing a mask having a pattern-like window on the surface of the planar light-emitting element, and a non-light-emitting portion may be employed. The organic layer forms a substantially non-luminous method of forming an extremely thick layer, and a method of forming an anode and/or a cathode into a pattern. The pattern can be formed by any of these methods, and a plurality of electrodes can be independently arranged to enable On/OFF switching, that is, a display element in the form of a segment can be obtained. Thereby, a display device which can represent numbers or characters, simple symbols, and the like can be obtained.

Further, in order to form a dot matrix element, the anode and the cathode may be arranged in a strip shape at the same time. Partial color or full color can be made by a coating method of a plurality of organic EL compounds having different luminescent colors, a method using a color filter or a fluorescent conversion filter, and the like. The dot matrix element can be driven passively or combined with a TFT or the like to be actively driven. These display elements are suitable as display devices such as viewing glasses for computers, televisions, portable terminals, mobile phones, car navigation systems, cameras, and the like.

In order to obtain the planar light emission by using the organic light-emitting device of the present invention, the planar anode and the planar cathode may be placed in a superposed manner. Such a planar light-emitting device is suitable for use as a surface light-emitting source, a backlight for a display device such as a liquid crystal display device, a planar illumination device, an interior decoration, and an outdoor decoration. Further, when a flexible substrate is used, it can also be used as a curved light source or a display device.

Example

Hereinafter, the present invention will be described in further detail by way of examples and comparative examples. However, the invention is not limited by its limitations.

For the sake of simplicity, the materials and the layers formed therefrom are abbreviated as follows.

ITO: indium tin oxide (anode)

Example 1

On one side of a 25 mm ² glass substrate, a substrate (NIPPO Electric, Nippo Electric Co., LTD.) having ITO (Indium Tin Oxide) strips of 4 mm wide as an anode and strip-shaped ITO electrodes was used. Fabrication of organic light-emitting elements. First, on the ITO (anode) with the ITO substrate, poly(3,4-extended ethyldihydroxythiophene) was obtained by spin coating. Polystyrene sulfonic acid (manufactured by Bayer, trade name "Pattron P") was applied under the conditions of a rotation number of 3,500 rpm and a coating time of 40 seconds, and then dried under reduced pressure in a vacuum dryer at 100 □. The conditions were dried for 2 hours and an anode buffer layer was formed. The film thickness of the prepared anode buffer layer was about 60 nm.

Next, a coating solution for forming a layer containing the phosphorescent compound is prepared. That is, the electron transporting polymer compound of polybis[4-(3,5-dimethyl-p-terphenyl)]-2,6-dimethyl-4-styrenephenylborane ( Writing poly-(vi2MB)) 11.5 mg, and a compound (pigmented) having a hole transporting property and a phosphorescent property (3-tert-butylphenylpyridine) ruthenium (III) (written as G3) 1.3 mg, dissolved The solution was filtered into a coating solution having a pore size of 0.2 μm in 387.2 mg of toluene (manufactured by Wako Pure Chemical Industries, Ltd.). The solid content contained in the coating liquid accounts for 10% of the pigment. Next, the prepared solution was applied onto the anode buffer layer by spin coating at a number of revolutions of 3000 rpm and a coating time of 30 seconds, and dried at 140 ° C for 30 minutes to form a light-emitting layer. The resulting luminescent layer has a film thickness of about 80 nm. Then, the substrate on which the light-emitting layer is formed is placed in the vapor deposition device, and the crucible is vapor-deposited to a thickness of 2 nm at a deposition rate of 0.01 nm/s, and the aluminum as a cathode is vaporized at a deposition rate of 1 nm/s. It was plated to a thickness of 150 nm to form element 1. In addition, the layer of tantalum and aluminum is formed by strips of two strips each having a width of 3 mm with respect to the direction in which the anode extends, and an organic light-emitting element having a length of 4 mm × a width of 3 mm is formed in each of the glass substrates. 4.

Using a programmable DC voltage/current source TR6143 manufactured by Yad Bentley Co., Ltd., a voltage is applied to the organic EL element to illuminate it, and the luminance of the light is used as "Teccon". The company's brightness meter BM-8 was measured. As a result, the external quantum efficiency (%) of the obtained element and the durability (hours) converted from the initial luminance of 100 cd/m ² are shown in Table 3 (components formed on one substrate each value) The average of 4).

Except as described in Table 1, the components 2 to 4 were produced in the same manner as the device 1 except that the concentration of the dye (G3) contained in the solid component was changed to 20%, 30%, or 40%. The EL light-emitting characteristics were also evaluated in the same manner as the elements 1 of these elements, and the results are shown in Table 3.

Comparative example 1

As shown in Table 2, in addition to the coating solution used, the electron transporting polymer compound (poly-(vi2MB)) used in the element 1 was changed to poly(N, N'-(3-A). Phenyl)-N-phenyl-N'-(3-vinylphenyl) 1,1'-biphenyl-4,4'-diamine-Co-bis[4-(3,5-di The same as the element 1 except for methyl-p-terphenyl)]-2,6-dimethyl-4-styrylphenylborane) (poly-(HMTPD)-poly-(vi2MB)) Create components 5~8. The EL light-emitting characteristics were also evaluated in the same manner as the elements 1 of these elements, and the results are shown in Table 3.

According to Table 3, it is understood that a light-emitting device (Comparative Example 1) produced by adding a phosphorescent compound (pigment) to a copolymer of a transporting polymerizable compound and an electron transporting polymerizable compound is used. A light-emitting device (Example 1) produced by adding a phosphorescent compound (pigment) to a polymer compound having electron transport properties has high external quantum efficiency and high durability.

In a light-emitting device (Comparative Example 1) produced by adding a phosphorescent compound (pigment) to a copolymer of a transporting polymerizable compound and an electron-transporting polymerizable compound, phosphorescence having a specific substituent is used. The luminescent compound (pigment) can be improved in dispersibility and the dye concentration can be improved. Further, in the present invention, as described above, it has been found that the carrier transportability of the phosphorescent compound which can be utilized is utilized. In other words, by combining: a pigment having carrier transportability and phosphorescence property, which is either a carrier transport property and an electron transport property (in the first embodiment, it is a hole transport property), and the other The polymer compound having carrier transportability (electron transportability in Example 1) can be achieved (the purpose thereof), and the durability is drastically improved.

Example 2

In the coating solution of the electron transporting compound and the phosphorescent compound (pigment) used in Example 1, a dye was further added to prepare a coating solution. That is, poly-(vi2MB) 170 mg, G3 pigment 19.2 mg, and [6-(4-vinylphenyl)-2,4-hexanedicarboxylate] bis[2-(2-pyridyl)benzene And 4.6 mg of thiazole (III) (written as R3) was dissolved in toluene (2.9 mg), and the resulting solution was filtered through a 0.2 μm pore size filter to prepare a coating solution. The solid content contained in the coating liquid accounts for a pigment concentration of G% of 20% and R3 of 7%. Further, the operation other than the coating solution was exactly the same as in Example 1, and the member 9 was produced.

The EL light-emitting characteristics were also evaluated about the element 9 in the same manner as the element 1, and the results are shown in Table 5.

Comparative example 2

The coating solution used for the component 9 was changed to (poly-(HMTPD)-poly-(vi2MB)) 89.3 mg and R3 was 6.7 mg, and dissolved in toluene 2.9 mg, and the obtained solution was made to have a pore diameter of 0.2. The μm filter was filtered and used as a coating solution. The solid content contained in the coating liquid accounts for a pigment concentration of R3 of 7%. Further, the operation other than the coating solution was exactly the same as in Example 1, and the member 10 was fabricated.

The EL light-emitting characteristics were also evaluated about the element 10 in the same manner as the element 1, and the results are shown in Table 5.

As shown in Table 5, it is understood that the light-emitting element (Comparative Example 2) produced by adding a phosphorescent compound (R3 dye) to the copolymer of the hole transporting compound and the electron transporting compound has In the electron transporting polymer, a high-concentration phosphorescent compound (G3 dye) system is added, and an R3 dye having a lower energy than the G3 dye is added, and the produced light-emitting element (Example 2) is an external quantum efficiency. High and durable.

1. . . Transparent substrate

2. . . anode

3. . . Positive hole transport layer

4. . . Luminous layer

5. . . Electron transport layer

6. . . cathode

Fig. 1 is a cross-sectional view showing an example of an organic light-emitting element of the present invention.

Claims (10)

An organic light-emitting element comprising an organic light-emitting element having at least one organic layer sandwiched between an anode and a cathode, wherein at least one layer of the organic layer contains a light-emitting layer of a polymer compound (I), and The polymer compound (I) has a structural unit derived from a polymerizable compound (a1) having a hole transporting property and a phosphorescent property, and a structural unit derived from the electron transporting polymerizable compound (b); The polymerizable compound (a1) is selected from the group consisting of the following formulae (E1-1) to (E1-9) and (E1-13) to (E1-32); the polymer compound (I) is in the total structure In the unit, the amount of the structural unit derived from the polymerizable compound (a1) is 15 to 30% by weight, and the compound having a hole transporting property in the light-emitting layer is formed by using only the polymerizable compound (a1). ; In the formula (E1-1), at least one of the hydrogen atoms is an amine group selected from an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, Substituting a group of alkoxy groups having 1 to 10 carbon atoms and a germyl group, and at least one of the hydrogen atoms is substituted with a polymerizable substituent represented by the following general formula (H1); Wherein R ²⁵ is a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms; and the hydrogen atoms in the formulae (E1-2) to (E1-9) and (E1-13) to (E1-32) are also It is the same as the hydrogen atom in the formula (E1-1). The organic light-emitting device of claim 1, wherein the polymerizable compound (a1) is represented by the formula (E1-1). An organic light-emitting element comprising an organic light-emitting element comprising at least one organic layer sandwiched between an anode and a cathode, wherein at least one layer of the organic layer contains a light-emitting layer of a polymer compound (II), and The polymer compound (II) has a polymerizable compound (a2) having a hole transporting property and a phosphorescent property, and a structural unit derived from the electron transporting polymerizable compound (b); the compound (a2) is a structural unit a group selected from the group consisting of the following formulae (E2-1) to (E2-9) and (E2-13) to (E2-32); the total amount of the compound (a2) and the polymer compound (II) The light-emitting layer contains the compound (a2) in an amount of 15 to 30% by weight; and the compound having a hole transporting property in the light-emitting layer is formed by using only the polymerizable compound (a2); In the formula (E2-1), at least one of the hydrogen atoms is an amine group selected from an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, Substituting a group of alkoxy groups having 1 to 10 carbon atoms and a group of carboxyalkyl groups; formula (E2-2) to formula (E2-9) and formula (E2-13) to formula (E2-32) The hydrogen atom in the ) is also the same as the hydrogen atom in the formula (E2-1). The organic light-emitting device of claim 3, wherein the compound (a2) is represented by the above formula (E2-1). The organic light-emitting device of claim 1 or 2, wherein the light-emitting layer contains the compound (d) having a phosphorescence capable of emitting light at a lower energy than the polymerizable compound (a1) Luminescence. The organic light-emitting device of claim 3 or 4, wherein the light-emitting layer contains the compound (d) having a phosphorescent property capable of emitting light at a lower energy than the compound (a2) . A display device in which the organic light-emitting device according to any one of claims 1 to 6 is placed in a superposed manner with a planar anode and a planar cathode, and the organic light-emitting device is used as a display portion. A surface-emitting light source, wherein the organic light-emitting device according to any one of claims 1 to 6 is disposed so as to overlap with a planar anode and a planar cathode, and the organic light-emitting device is used as a surface-emitting portion. . A backlight for a display device, characterized in that the organic light-emitting device according to any one of claims 1 to 6 is disposed so as to overlap a planar anode and a planar cathode, and the organic light-emitting device is used as a backlight. An illuminating device characterized in that the organic light-emitting device according to any one of claims 1 to 6 is disposed so as to overlap with a planar anode and a planar cathode, and the organic light-emitting device is used as an illumination portion.